1. Field of the Invention
The present invention relates to a projector apparatus used for a projector type image display apparatus for displaying a projected image on a screen, and more particularly to a lens mounting mechanism for mounting and dismounting a lens barrel.
2. Description of the Related Art
An example of construction of a projector apparatus in the related art will be described. The projector apparatus is provided in an enclosure with a light source such as metal halide lamp, a dichroic mirror for separation, a reflection mirror, a liquid crystal panel, a dichroic mirror for photosynthesis, an optical path adjusting mechanism including a pair of liquid prisms, and a projecting lens.
A light beam emitted from the light source is divided into Red, Blue, and Green three primary colors by the dichroic mirror for separation. The coefficient of transmission of the divided light beams is modulated depending on image information of the respective color components at the liquid crystal panel on the respective optical path. The modulated light beam is combined by the dichroic mirror for photosynthesis. The combined light beam is extended and projected on a screen by a projecting lens after the optical path thereof is adjusted by the optical path adjusting mechanism.
The projector apparatus for extended projection an image as described above is used at places under different conditions in which the distances to the screen and/or the sizes of the screen differ from each other.
Therefore, in order to improve the image accuracy, such difference in conditions are compensated by replacing lenses of the projector apparatus.
In the case where the lens can be replaced, it is convenient such that an alternate lens can be used for repair and the like, or only the lens unit can be replaced when replacement of a lens component is required.
The way to replace the lens of the projector apparatus in the related art will be described. FIG. 12 is a schematic view, partially broken away, of a projector apparatus in the related art showing a portion where the lens is replaced.
In FIG. 12, a projector apparatus 101 is mainly composed of an apparatus body 102 and a lens barrel 103. The lens barrel 103 is provided with a lens disposed therein and thus the lens can be replaced by replacing the lens barrel 103.
A method of mounting the lens barrel 103 employed in the related art is such that four points on the flange portion 103a of the lens barrel 103 are secured to predetermined positions of the apparatus body 102 with screws 104, as shown in FIG. 12.
However, in the related art, when the projector apparatus is significantly bulky, the lens barrel itself is quite heavy, and thus is hard to deal with. Furthermore, since the outer diameter is also large, when it is rotated, it may interfere with peripheral components and become damaged. Therefore, it is difficult to mount and dismount the heavy lens barrel while keeping the posture and the position stable.
In particular, since the lens barrel is bulky, and thus the space around the lens barrel is limited, the operator is hard to insert his/her hand for lifting the lens barrel, and the only possible way is to secure it with screws using a specific tool, which is not preferable in workability.
In addition, the operation itself is very troublesome because it requires a plurality of operators including a person who lift the lens barrel and a person for screwing with the specific tool.
In view of such circumstances, an object of the present invention is to provide a lens mounting mechanism and a projector apparatus in which mounting and dismounting of the lens barrel can be performed easily.
In order to achieve the object described above, a lens mounting mechanism according to the present invention includes:
a barrel mounting member mountable on an outer periphery of a lens barrel having a lens disposed therein, the barrel mounting member having a cylindrical portion a flange portion extending radially outwardly from one end of the cylindrical portion, and projections projecting radially outwardly from the other end circumferential plural positions of the cylindrical portion;
a base member fixed to an apparatus body to which the lens barrel is mounted, the base member having a hole portion through which the cylindrical portion is inserted together with the lens barrel, a groove formed on an inner periphery of the hole portion for enabling the projections to be inserted, and an opening end surface of the hole portion to which the flange portion is abutted; and
a ring member rotatably disposed in a state of being clamped by the base member, the ring member having a recess on an inner periphery thereof for enabling the projections to be inserted in the same manner as the groove, wherein the lens barrel is mounted to the apparatus body by rotating the ring member and aligning the groove on the base member and the recess on the ring member in the circumference direction, inserting the lens barrel into the hole portion until the flange portion of the barrel mounting member abuts against the opening end surface, and subsequently rotating the ring member for displacing the recess and the groove in the circumferential direction so that the projections are locked by the ring member and thus the barrel mounting member is fixed.
Therefore, the lens barrel can be mounted only by inserting the flange portion of the barrel mounting member abuts against the opening end surface and then rotating the ring member.
Therefore, if the lens barrel can be inserted while aligning the projections of the barrel mounting member along the groove of the hole portion of the base member, the heavy lens barrel can be mounted and dismounted while keeping the posture and the position stable.
Since insertion can be made with the posture and the position of the lens barrel kept stable and the mounting and dismounting can be performed only by one-touch operation only by rotating the ring member without using the specific tool for fixation, workability is improved and the operation can be performed by a single operator.
Preferably, the lens mounting mechanism is provided with an urging device for urging the projections in a lens barrel insertion direction when the projections are locked by the ring member.
Accordingly, the barrel mounting member can be fixedly secured, and rattling of the lens barrel is prevented.
Preferably, the urging device has a bent portion formed by bending a portion of the ring member for locking the projections in the lens barrel insertion direction.
Accordingly, the projection can be urged by being pushed by the bent portion of the ring member.
Preferably, the spring device has a spring member including a leaf spring formed at a position for locking the projections, the spring member stacked on a side of the lens barrel insertion direction of the ring member.
Accordingly, the projections can be urged by being pressed by the leaf spring.
Preferably, the lens mounting mechanism is provided with a locking mechanism for positioning the ring member at a position where the grooves and the recesses are aligned in the circumferential direction and at a position where the grooves are displaced from the recesses in the circumferential direction.
Accordingly, accuracy of positioning of the ring member when moved circumferentially is improved.
Preferably, the locking mechanism includes a positioning hole formed on the base member; a fixed member fixedly mounted to the ring member; a sliding member having a projection to be engaged with the positioning hole and being slidably mounted to the fixed member so as to be capable of releasing engagement of the projection with the positioning hole; and a second urging device for urging the sliding member in a direction in which the projection engages the positioning hole, wherein the engagement of the projection with respect to the positioning hole is released to allow the ring member to rotate by sliding the sliding member against the urging force of the second urging device, and the ring member is positioned at the position where the groove and the recess are aligned in the circumferential direction and at the position where the groove is displaced from the recess in the circumferential direction by engaging the projection with the positioning hole.
Accordingly, by sliding the sliding member, the projection can be pulled out from the positioning hole and engagement between the projection for positioning and the positioning hole is released. In addition, since the sliding member slides in the engaging direction spontaneously by an urging force of the second urging device if no force is exerted to the sliding member in the sliding state, the operation of the operator may be significantly simplified.
A projector apparatus according to the present invention includes the lens mounting mechanism; the lens barrel which is mountable and dismountable by the lens mounting mechanism; and the apparatus body to which the lens barrel is mounted.